2材料物理课件_(12).ppt
Polymer Solution,What is polymer solution?,Why to study polymer solution?,HOW to study polymer solution?,3 Questions,What is polymer solution?,polymer + polymer,polymer + solvent,Traditional,Cover,Why to study polymer solution?,Study,Best method on investigation of a single polymer,Applictions,Bond,Dope,Filature,Plastic enhanced,Blend,HOW to study polymer solution?,Polymer solution process How to select a solvent Solution state：Interaction solution and separate Solution thermodynamics,Josiah Willard Gibbs (1839-1903),Gibbs 方程 G=H-TS,18731878,Insluable，Phase Seperate, 状态,Key points for polymer dissolving,Linear polymers,Swelling to solution,Cross-linked polymers,Only swelling,Crystalline polymers,Melting to solution,Solvent selection,Similar dissolve mutually theory,Polarity,Polarity,Non- Polarity,Non- Polarity,(2) Similar solubility parameter,Gibbs free energy 自由能,Enthalpy 焓,Entropy 熵,Condition of solution,During solution process,Solubility parameter = 1/2 =,CED Cohesive energy density,Therefore HM is the key,Polar polymer to polar solvent，HM 0, Self-solution-process.,(b) In general，HM 0, Solution is depended on the comparison of HM and TSM. HM TSM, Soluble 。HM need be more little 。,Hildebrand equation,1, 2 Volume fraction of Solvent and polymer, respectively .,1, 2 Solubility parameter fraction of Solvent and polymer, respectively .,VM Volume after blending,Hildebrand J., Scott R.L., Solubility of Nonelectrolytes, Reinhold Publishing Corporation, New York, Chapter 7 (1949),Hildebrand function is good for non- or weak polar polymer For polar polymer, Hansen公式: Blend solvent：,How to get ?, = 1/2 =,(a) Swelling method：,Cross-linked polymer is dissolved in different solvents. The of the solvent with the largest swelling volume is the of polymer.,(b) Viscoelasticity method,Polymer is dissolved in different solvents. The of the solvent with the largest solution viscoelasticity is the of polymer.,聚合物各结构基团的摩尔引力常数,重复单元的摩尔体积,(c) Calculation,PMMA,F=269+65.6+668.2+303.4*2=1609.6,V=M/=(5C+2O+8H)/1.19=100/1.19, status,Good solvent,Bad solvent,“Polymer-Solvent interaction factor 11/2”,Electron acceptors Electron donors,Thermodynamical properties of the flexible chain polymer solutions,ideal solution 理想溶液,Same 1,No volume change，no heat change.,M mixing i - ideal,However, the ideal solution is nonexistence,Difference between the polymer solution and the ideal solution:,HM is not 0。 SMSi,3.2.2 Thermodynamics of polymer solutions Flory-Hunggins Theory (Mean-field theory),Analogous to regular solution in alloys,A-B alloys,Polymer solution,Three Hypotheses 三点假设,Polymer in solution is arranged like crystal. Polymer is flexible。 Chains of polymer is dissolved uniformly 。,Dissolving process,Polymer entity,Polymer disorientation,Solvent,Polymer Solution,Sdisorientation,Ssolvent,Sdisorientation,（5） - state（ 状态）,Similar to ideal solution, Condition - 状态,（6）Discussion of Hunggins parameter,Chemical potential,More stable,Good solvent,良溶剂,Chemical potential,Not stable,Bad solvent,劣溶剂,Phase equilibrium of polymer solution,Osmotic pressure ,Solution,Solvent,Semipermeable membrane 半透膜： 允许小分子通过，不允许大分子通过。,What is the physical meaning of the second Virial coefficient A2?,Molar volume of solvent,Density of solute,What we can get from the following equation?,(2) A2 Second Virial coefficient,Intercept=,Slope coefficient=,Intercept,slope,Discussion of A2, status,良溶剂,劣溶剂,A2=0,A20,A20,Huggins parameter,Status,Second Virial coefficient,Discussion of the plot,(a) Add bad solvent into good solvent,(b) Decrease temperature, solvent, temperature,Stable, metastable and non-stable regions,GM can be substituted by 1 and Temperature,Critical point,Different phase equilibrium diagrams,Phase separation and dissolution are controlled by three variables: temperature, pressure, and concentration.,LCST- Low critical solvency temperature,UCST- Ultra critical solvency temperature,Typical polymer-solution phase equilibrium diagram,Weak concentration,High concentration,Characteristic- Non-symmetry,e.g. PVC raincoat, using plasticizer,
